There must be a deviancy, an insanity even, that afflicts those who are motivated to kill for their beliefs. Such individuals — prepared to bomb a concert packed with children and teenagers or mow down pedestrians on a bridge — must lie somewhere on the spectrum of madness. This tempting rationalisation of terrorism has little basis in scientific evidence, according to psychologists. “It is not true that terrorists share a common psychological profile,” wrote Paul Gill and Emily Corner, from University College London. “No [single] mental health disorder appears to be a predictor of terrorist involvement.” READ MORE